In order for the mechanical and electrical intake contact and the sliding electrical contact of a collection supply shoe on a linear collection structure to operate correctly, several conditions must exist.
First, the mechanical contact must occur smoothly and progressively. Next, the electrical contact must be established correctly and continue for the entire length of the collection structure.
To do this, a mechanical means must be provided to achieve and maintain nearly perfect mechanical contact between the two opposing surfaces. The quality of this contact necessitates precise geometry and a means for recovering any deviations and irregularities during the contact phase, that is, the electrical supply phase.